gauriranjekar wrote:
Chlorination is used in industry for the purification of water; 1gm solution of chlorine will remove half of the germs in 1 liter of water. If water containing less than 0.09% of germs is considered clean, what is the minimum amount of chlorine required to purify 150 liter of water containing 0.3 liter of harmful substances?
A. 1
B. 2
C. 3
D. 4
E. 5
Are you sure the question you typed is correct? Can you put up a screenshot from the original source? I think the question is ambiguous and options make no sense.
1 gm solution of chlorine removes half the germs in 1 liter of water. 150 liter of water will need 150 gm solution of chlorine to kill half the germs. Currently, the water has .3/150 *100 = .2% harmful substances.
Adding 150 gms of chlorine will make it .1% harmful substances.
Now the issue is that do we need another 150 gms of chlorine solution (which will bring the harmful substances down to .05%) or a small amount which will bring the harmful substance concentration down to 0.09% since we need to find the minimum amount of chlorine solution.
The options 1, 2, 3, 4, 5 are of no help!
Yes, the question is right. I am attaching the screenshot anyway.
And as per the explanation provided in the question source, that additional one gram is required to bring down the harmful substances to 0.05%.